Both bi-fold and tri-fold frames for supporting futons are well known in the prior art. The bi-fold frames include two sections which generally are movable relative to each other, between a "couch" orientation, in which the sections are disposed to form a seat and backrest, and a "bed" orientation, wherein futon-supporting surfaces of the two sections generally lie in the same plane. In this latter orientation the futon functions as a mattress, with the distance between the front edge of the seat section and the rear edge of the backrest section constituting the width of the bed, and with the length of the frame, from one side edge to the other side edge, constituting the length of the bed.
In order to maintain the sections of the bi-fold units in the required orientation to provide a seat and backrest for supporting a futon, it is necessary to provide a locking arrangement between the pivotal sections. Although some of the prior art locking arrangements have been fairly simple in construction, they have been very difficult to operate.
In one prior art construction pivoting locking blocks are rotatably secured to transversely-spaced side frame members of the backrest section. These blocks are designed to engage the upper surface of the section forming the seat, to prevent inadvertent movement of the backrest section relative to the seat section when the frame is being employed in its "couch" orientation. Although this pivoting block arrangement may provide a satisfactory locking force to maintain the bi-fold sections in the "couch" orientation, it is quite cumbersome to operate the blocks for the purpose of converting the frame to its "bed" orientation, and then back to its couch orientation. Specifically, in order to make these conversions it is necessary for the person to physically bend over and rotate the block on each side frame of the backrest section. This generally requires the user to move from one side of the frame to the other, and in some cases, may even require two individuals to simultaneously move the pair of pivoting blocks. Moreover, since the pivoting blocks generally are adjacent the lower end of the backrest section (in order to properly engage the seat section) the person operating the frame often needs to bend into an uncomfortable position to operate the pivoting blocks.
In another arrangement wooden dowel pins are provided to fit into aligned holes of the seat section and backrest section, at each side of the construction, when the seat and backrest sections are disposed in the "couch" orientation. In other words, it is in this orientation that the openings are aligned to receive the dowel pins. In order to convert this latter frame construction into a bed it is necessary for a person to first remove the dowel pin from one side of the construction, and then from the other side. Moreover, it is quite inconvenient and cumbersome to again try to reposition and lock the frame members in the "couch" orientation.
In view of the problems associated with prior art bi-fold constructions, a need exits for a economical and simple-to-operate bi-fold unit which can easily be converted between a "couch" and a "bed" frame orientation, without requiring a person to move from one side of the frame to the other.
Tri-fold frame constructions for futons also have been around for years, and actually have been the standard frame construction in the industry. Although a variety of different mechanisms are employed to permit these tri-fold constructions to be oriented into different positions, the operating mechanisms often are difficult to use, and in many cases can actually damage the floor or other supporting surface when being opened from a seating piece orientation to a bed frame orientation.
One of the major disadvantages of prior art tri-fold constructions is the difficulty of converting the frame from a bed to a couch. First, the futon (which functions as the mattress of the bed) must be folded in half to expose the back or rear portion of the frame. Thereafter, the exposed frame section must be raised and locked, and then the entire frame, with the futon on it, must be slid back to the original position, usually against a wall. This is not an easy task, in view of the fact that the combined frame and futon weighs on the order of 100-140 pounds. Thus, what is intended to otherwise be a versatile piece of furniture, in actuality is difficult to use, and therefore unappealing. In fact, these prior art constructions may be impossible to operate by many individuals, such as individuals of small stature, individuals having little strength, or individuals that are elderly and/or handicapped.
Another disadvantage of some prior art tri-fold constructions, becomes apparent when converting the frame from a "couch" or "chair" position, to a bed configuration. In order to accomplish this conversion the seat section generally is pulled out first, to thereby cause all three sections to pivot relative to each other. However, at some point the combined weight of the frame and futon overcomes the frictional resistance to sliding movement of the back section, resulting in both the middle and back sections collapsing to the floor. This often provides a very loud and disturbing noise, particularly in situations where the floor is not carpeted, which is often the case in studio apartments, dormitories and temporary housing in which the use of futon frames is becoming quite popular.
Other prior art convertible furniture constructions are shown in U.S. Pat. Nos. 4,875,244; 4,829,611; 4,692,952; 4,642,823; 4,538,308 and 2,294,475. However, none of the prior art constructions known to applicant solve the heretofore mentioned problems associated with bi-fold and tri-fold frame constructions.
In view of the above deficiencies a need exists in the industry for a low cost, convenient-to-operate, tri-fold futon frame which is easily convertible between multiple positions, and which does not suffer from the above-enumerated disadvantages of the prior art.